Reactions with Heterocyclic Amidines, XI. Syntheses of New 2‐Aminopyrazolo[1,5—a]pyrimidines and 2‐Amino[1,5‐c]‐as‐triazines

Abstract

Several new aminopyrazolo [ l,S-u]pyrimidines were synthesised by condensation of 33-diami-no4-(ethoxycarbonyl)pyrazoIe (1) with b-bifunctional reagents. The azo analogues of pyrazolo [l,5-u]pyrimidines, i. e. pyrazolo[l,4-c]-ar-triazines, were synthesised by coupling of diazotized 1 with agents containing active hydrogen. Reaktionen mit heteroqLliscaen Amidinen, ll. M i t t . : Syntheae e w e r nener Aminopyrrzolo[l,S-n]pyrhnicUn-Derivate und 2 -A m i n o [ l , S -c ] -~-t eEinige neue Aminopyrazolo[ 1,5-a]pyrimidin-Derivate wurden durch Umsetzung von 3,5-Diami- no-4-ethoxycarbonyl-pyrazol(l) mit p-bifunktionellen Reagenzien synthetisiert . Die Azoanalogen Pyrazolo[l,S-c]-as-tri~ne wurden durch Umsetzung von diazotiertem 1 mit Reagenzien mit aktivem Wasserstoff hergestellt.Schistosomiasis is considered to be one of the most difficult diseases to treat"). Accordingly considerable attention has been directed toward development of chemotherapeutic agents. Recently Sengu at a l ' ) have reported that certain pyrazolo[ 1 ,5-u]pyrimidines have considerable antischistosomal activity. 0365-6233/lWM84713 S U2.50/0 0 Verlae Chemie GmbH, Weinheim 1983 714 Kandeel, Baghos, Mohareb and ElnagdiArch. Pharm.

Chitosan as heterogeneous catalyst in Michael additions: The reaction of cinnamonitriles with active methyls, active methylenes and phenols

“…1 Since then plenty of acyclic active methylenes, [2][3][4][5] cyclic active methylenes, 6-7 functionally substituted alkylazoles, [8][9][10][11] alkylazinylcarbonitriles [12][13] as well as other nucleophilic reagents have been added during the 1970's and 1980's. [14][15][16][17][18] Generally, reactions of benzylidene-malononitrile with active methylene ketones give aminopyrancarbonitriles. Alternatively, cyclic ketones have been reported to yield either tetrahydronaphthalenes or tetrahydrobenzopyrans 7,16,19 depending on substitution pattern.…”

Synthesis and Evaluation of Novel [1,2,4]Triazolo[5,1‐c][1,2,4]‐triazines and Pyrazolo[5,1‐c][1,2,4]triazines as Potential Antidiabetic Agents

“…Cyclization of 10a , b proceeds smoothly in refluxing pyridine to give 3‐cyanopyrazolotriazines 11a , b (Scheme ). Pyrazolotriazines with similar structure are described in works .…”

Chemistry of Pyrazole-3(5)-Diazonium Salts (Review)*

“…A non-obvious method for the preparation of diazonium hydrogen sulfates 1 is based on the treatment of pyrazolylhydrazone 9 with concentrated sulfuric acid [45] We should note that diazotization of heterocyclic substrates usually produces the corresponding diazonium salts, and only in rare cases, such as pyrazole series, it is possible to isolate diazo compounds 2. The latter are usually obtained by adding base (Na 2 CO 3 , AcONa, NaOH, Et 3 N) to a freshly prepared solution of diazonium salts in order to bind the acid [1, 2,20,22,[46][47][48].…”